TYLOSIN CONTAINING SUSTAINED RELEASE VETERINARY COMPOSITIONS

Abstract: A sustained release veterinary composition, for intra-muscular and subcutaneous administration comprises Tylosin and an oily vehicle containing a gelling agent, wherein the gelling agent may be an aluminium salt of a fatty acid such as stearic acid and the oily vehicle may be a low viscosity polyol diester of a short chain naturally derived fatty acid such as propylene glycol dicaprylate/dicaprate.

Description: TYLOSINCONTAININGSUSTAINEDRELEASEVETERINARYCOMPOSITIONS This invention relates to a pharmaceutical preparation and in particular to a veterinary preparation for intra- muscular and subcutaneous administration of Tylosin. Tylosin is a member of the macrolide group of antibiotics which is indicated clinically for the treatment of many bacterial infections in beef cattle, non-lactating dairy cattle and swine. Tylosin is available as a parenteral product containing 50 mg/ml or 200 mg/ml active ingredient typically administered once daily for a three day period. However such preparations provide quick onset and short duration of action and are associated with irritancy at the site of injection. Thus there is a clinical need for a Tylosin preparation which provides a sustained release of Tylosin over a period of days and may be administered with minimal adverse tissue reactions. An object of this invention is to obviate or mitigate the aforesaid disadvantages. Accordingly this invention aims to provide a veterinary preparation for intramuscular and subcutaneous administration comprising Tylosin in a system which promotes sustained release of the active ingredient. According to this invention there is provided a sustained release composition, comprising Tylosin and an oily vehicle containing a gelling agent, e.g. an aluminium salt of a fatty acid. Preferably the oily vehicle is a low viscosity polyol diester of a short chain naturally derived fatty acid, typically propylene glycol dicaprylate/dicaprate. Preferably this vehicle is that which is obtainable under the trade name Neobee Oil. The oily vehicle is preferably present in an amount of from 70-90%, most preferably 84% by weight of the composition. The gelling agent present is typically aluminium distearate. The aluminium distearate may be present in an amount of from 0.75-1.25%, but most preferably 0.94%, by weight. Other stearates may also be used to replace aluminium distearate, namely aluminium moπostearate or aluminium tristearate. Preferably the aluminium monostearate is present in an amount of from 1-3% but most preferably about 1.8% by weight. Alternatively, an equivalent amount of aluminium tristearate should be present. This invention further provides a method for incorporation of an active ingredient such as Tylosin into the oily vehicle. Preferably, Tylosin is present in an amount from 3-30% but most preferably approximately 15% by weight per unit volume. The particle range of the active ingredient is preferably controlled so that 90% of particles have a major dimension of less than 25 μm as measured using the Coulter Counter technique or an equivalent dimension when measured using alternative methods. More preferably the particle size should be less than 10 μm. The invention also provides a process for preparing a veterinary preparation for intramuscular and subcutaneous administration as hereinbefore defined comprising the steps of:- Mixing a pharmaceutically acceptable (sterile) vehicle and an agent for sustained release and applying sufficient heat to permit adequate mixing, allowing the mixture to cool to form a gel base, and adding Tylosin to form a suspension thereof in the gel base. The invention may be more clearly understood from the following description of a formulation thereof given by way of example only: FORMULATION QUANTITY (σ/1) Tylosin 150.00 Aluminium distearate 9.35 Neobee Oil M20 840.65 The Neobee Oil is placed in a stainless steel pressure vessel in an aseptic area. The contents of the vessel are then heated to 160°C and the temperature is maintained for one hour to sterilise the contents of the vessel. This is allowed to cool and, when the temperature reaches 120°C, the aluminium distearate is added with gentle stirring until dissolution has occurred. The solution is then allowed to cool without further stirring until ambient temperature is reached. At this stage Tylosin is added and suspended aseptically. To achieve the required particle size of Tylosin, the product may be passed through a conventional milling device. Preferably this milling device is a bead mill e.g. that sold under the name Dyno Mill. The final product is a stable off-white/cream suspension which can be used for the prophylaxis and treatment of cattle and pigs infected by micro-organisms sensitive to Tylosin. In general, the product is best administered by intramuscular injection. The optimal concentration of Tylosin is 150 mg/ml. This has been chosen after consideration of the dose required to produce the required therapeutic effect after a single administration. In the selection of appropriate oily vehicles, several candidates were initially examined for their suitability in this preparation. Resultant from this a polyol diester of short chain naturally derived fatty acids, propylene glycol dicaprylate/dicaprate was chosen. This oil has low viscosity, low setting point, and is therefore a useful vehicle for parenteral products. Aluminium distearate is used to gel oily vehicles and, in so doing, to promote sustained release of Tylosin at the site of injection. The process of heating the vehicle, addition of aluminium stearate and allowing the product to cool results in a stable thixotropic gel which both ensures the retention of Tylosin in suspension and accuracy of dosage. The amount of aluminium distearate used is chosen such that there is facilitation of formation of suspension and syringeability. The particle size range of Tylosin used is of vital importance as it ensures good resuspension of product and contributes to the sustained activity of the product. For these reasons it is preferable that 90% of particles have a major dimension of less than 25 μm as measured using the Coulter Counter technique or an equivalent dimension when measured using alternative techniques. Indeed it is more preferable that the particle size is less than 10 μm. The efficacy of invention will now be further described by way of the following test examples: Example 1 A 15% (w/v) Tylosin in Neobee oil (identified hereinafter as "Tylosin LA") was prepared by procedures following usual industry practice. Administration thereof by intramuscular injection to cattle at a dose rate of 20 mg/kg bodyweight was carried out to enable a study of the plasma levels and hence the efficacy of the product to be made. The tylosin values at each timepoint were meaned, the standard errors determined and the results presented in Table 1 and also graphically (Graph 1) . The mean C max was 2.612 ± 0.249 μg/ml, achieved after 3 ± 0.5 hours. The mean area under the curve (AUC) was 31.32 ± 1.84 μg/ml.hr. The half- life of elimination was found to be 10.01 ± 1.7 hours. TABLE 1: Plasma Levels of Tylosin in Cattle After Treatment with Tylosin LA. TIME (Hours) AFTER ADMINISTRATION 0 2 3 4 8 MEAN ND 1.686 2.434 2.160 1.990 1.269 12 24 32 48' 56 72 MEAN 0.839 0.298 0.231 0.111 ND ND Limit of Detection : 0.10 μg/ml ND - Not detectable Example 2 An efficacy study in pigs following the intramuscular administration of Tylosin LA and a proprietary Tylosin product in the treatment of induced respiratory tract injections was carried out. This study demonstrated the efficacy of parenterally administered Tylosin in the treatment of an induced, acute, lower respiratory tract infection of Pasteurella multocida and Mycoplasma hypopneumonia in pigs. The study involved a total of 40 pigs. Three treatment groups were involved in this study: l. Tylosin LA at 20 mg/kg bodyweight on a single occasion. 2. Tylosin LA at 30 mg/kg bodyweight on a single occasion. 3. Proprietary Tylosin product (50 mg/ml) at 3 daily 10 mg/kg bodyweight doses. A summary of the results for the mean body temperature and the mean clinical scores are presented in Tables 2 and 3 respectively. A repeatable artificial infection model of severe clinical pneumonia was induced in the pigs. Treatment with one of 3 dose regimes was utilised to compare the efficacy of Tylosin LA and the proprietary Tylosin product. The clinical response to treatment was excellent in that all animals which survived the first 24 hours after inoculation showed significant clinical improvements similar to the field treatment of natural clinical cases with antibiotic therapy. The use of weighted scoring system has shown that a single administration of Tylosin LA at either of the dose rates used (20 mg/kg or 30 mg/kg administered on a single occasion) demonstrated statistically significant improvements in recovery rates when compared to a 3 day course of treatment with the proprietary Tylosin product. It can therefore be concluded that Tylosin LA in a single administration of supply will be at least as effective as the course of treatment using proprietary Tylosin product when used in the treatment of pneumonia. TABLE 2 : Mean Body Temperature TIME (Hours TYLOSIN LA TYLOSIN LA PROPRIETARY From First 20 mg/kg 30 mg/kg PRODUCT Administration) (n = 11) (n = 12) (50 mg/ml) 3 x 10 mg/kg (n = 12) MEAN MEAN MEAN -96 102.32 102.08 102.09 -88 102.06 102.12 102.09 -72 102.18 102.09 102.22 -64 102.11 102.08 102.22 -48 102.17 102.18 102.09 -24 102.20 102.09 102.18 -16 102.14 102.25 102.18 0+ 104.63 104.68 104.38 4 104.33 104.65 104.47 8 103.75 103.97 103.90 12 103.38 103.62 103.62 24++ 103.20 103.20 103.53 32 103.07 103.07 103.60 48+++ 102.69 102.82 103.40 56 102.96 102.90 103.48 72 102.78 102.33 102.97 96 102.56 102.37 102.87 120 102.51 102.30 102.72 192 120.38 102.42 102.83 240 102.40 102.30 102.78 288 102.24* 102.29 102.93 360 102.49* 102.25 102.43 * n = 10 for these timepoints. + Administration of Tylosin LA and first administration of Proprietary Product. ++ Second administration of Proprietary Product. +++ Third administration of Proprietary Product. TABLE 3: Mean Clinical Scores TIME (Hours . TYLOSIN LA TYLOSIN LA PROPRIETARY From First 20 mg/kg 30 mg/kg PRODUCT Administration) (n = 11) (n = 12) (50 mg/ml) 3 x 10 mg/kg (n = 12) MEAN MEAN MEAN -16 0 0 0 0+ 36.2 35.9 35.0 4 34.3 35.7 34.8 8 29.9 31.4 30.0 12 26.4 29.8 30.4 24++ 22.1 24.3 27.1 32 21.8 22.3 28.9 48+++ 17.3 18.8 24.6 56 18.2 19.3 24.9 72 15.0 16.8 20.1 96 12.5 17.3 21.0 120 11.2 13.8 17.5 192 9.3 10.5 14.3 240 8.8 9.2 11.9 288 8* 8.9 11.3 360 5.7* 7.7 8.4 n = 10 for these timepoints. + Administration of Tylosin LA and first administration of Proprietary Product. ++ Second administration of Proprietary Product. +++ Third administration of Proprietary Product.

Claims: Claims 1. A sustained release composition, comprising Tylosin and an oily vehicle containing a gelling agent. 2. A sustained release composition according to claim 1 wherein the gelling agent is an aluminium salt of a fatty acid. 3. A sustained release composition according to claim 2 wherein the fatty acid is stearic acid. 4. A sustained release composition according to claim 1 or claim 2 wherein the oily vehicle is a low viscosity polyol diester of a short chain naturally derived fatty acid. 5. A sustained release composition according to claim 4 wherein the oily vehicle is propylene glycol dicaprylate/dicaprate. 6. A sustained release composition according to claim 1 wherein the oily vehicle is that which is obtainable under the trade name "Neobee Oil". 7. A sustained release composition according to claim 1 or claim 2 wherein the oily vehicle is present in an amount of from 70-90% by weight of the composition. 8. A sustained release composition according to claim 1 or claim 2 wherein the oily vehicle is present in an amount of 84% by weight of the composition. 9. A sustained release composition according to claim 3 wherein the gelling agent is aluminium distearate. 10. A sustained release composition according to claim 9 wherein the aluminium distearate is present in an amount of from 0.75-1.25% by weight of the composition. 11. A sustained release composition according to claim 9 wherein the aluminium distearate is present in an amount of from 0.94% by weight of the composition. 12. A sustained release composition according to claim 3 wherein the gelling agent is selected from the group consisting of aluminium monostearate, aluminium distearate and aluminium tristearate. 13. A sustained release composition according to claim 12 wherein aluminium monostearate is present in an amount of from 1-3% by weight. 10 14. A sustained release composition according to claim 12 wherein aluminium monostearate is present in an amount of about 1.8% by weight. 15 15. A method for incorporation of an active ingredient such as a macrolide antibiotic, e.g. Tylosin into an oily vehicle comprising the steps of controlling the particle size of said active ingredient so that 90% of particles have a major dimension of less than 25 μm as measured using the Coulter 20 Counter technique and mixing said active ingredient into said oily vehicle. 16. A method according to claim 15 wherein the active ingredient is Tylosin which is present in an amount from 3-30% 25 by weight per unit volume. 17. A method according to claim 15 wherein the particle range of the active ingredient is controlled so that 90% of particles have a major dimension less than 10 μm. 30 18. A process for preparing a veterinary preparation for intramuscular and subcutaneous administration comprising the steps of:- f 35 (i) mixing a pharmaceutically acceptable vehicle and an agent for conferring sustained release properties and applying sufficient heat to permit adequate mixing, (ii) allowing the mixture to cool to form a gel base, and (iii) adding Tylosin to form a suspension thereof in the 40 gel base. 19. A process according to claim 18 wherein the concentration of Tylosin is 150 mg/ml. 20. A method of treating livestock for the purposes of countering infection by micro-organisms sensitive to Tylosin comprising the intramuscular or subcutaneous administration thereto of a sustained release composition, comprising Tylosin and an oily vehicle containing a gelling agent, in an amount of from 20 to 30 mg/kg (body weight) administered on a single occasion.

Inventors: HOLMES DREW, PATTERSON ALAN, HOLMES, DREW, PATTERSON, ALAN
Applicants: HOLMES DREW, NORBROOK LAB LTD, PATTERSON ALAN, HOLMES, DREW, NORBROOK LABORATORIES LIMITED, PATTERSON, ALAN
Application year: 1994
Main classification: A61K31
IPC codes: A61K9, A61K31, A61K47